Youth movement: It started last season when the veteran Smith lost his job to Colin Kaepernick, who dazzled with his athleticism. How Kaepernick does in his encore will be a deciding factor in whether the 49ers can get back to the Super Bowl.

Best young player: DE Aldon Smith, left.

Pressure’s on: TE Vernon Davis. The 49ers lost No. 1 receiver Michael Crabtree to an Achilles injury in May, leaving Kaepernick without his favorite target. Davis could help his young quarterback out by stepping into that role.

Youth movement: The Seahawks let the veteran linebacker Hill walk in free agency and will replace him with K.J. Wright, a third-year veteran.

Best young player: CB Richard Sherman. It took only one full year as a starter for Sherman to establish himself as the best cornerback in the NFL. Entering his third year, Sherman is in the early prime of his career.

Pressure’s on: DT Tony McDaniel. There aren’t many weaknesses on the Seahawks, but their run defense toward the end of last season was one of them. McDaniel started just two games in four years with Miami.

Youth movement: The Rams let Amendola and Brandon Gibson go in free agency, meaning they lost two of their top receivers over the last few seasons. To replace them, they’ll count on Austin — whom they traded up with the Bills in the draft to get — and Chris Givens, Austin Pettis and Brian Quick.

Best young player: DE Robert Quinn. Teamed with Chris Long, Quinn forms one half of a dynamic pass-rushing pair. The North Carolina product had 10.5 sacks in his second year.

Pressure’s on: RB Daryl Richardson. He’s tasked with replacing one of the best players in franchise history in Jackson.

Youth movement: The Cardinals declined to re-sign the veteran safety Wilson, one of their most productive players, and will replace him with Rashad Johnson. He has 14 starts in his first four seasons.

Best young player: CB Patrick Peterson. One of the league’s most exciting returners, Peterson developed last season into one of the best cover corners, as well.

Pressure’s on: LB Karlos Dansby. The veteran returns to the team he spent his first six seasons with. He’ll have to replace inside LB Daryl Washington, one of the best players at his position, who is suspended for the first four games of the season. –J.S.